The present invention relates to locks and methods for locking circuit breaker switches, as well as to tools for making such locks.
A circuit breaker of the type relevant to this invention has a toggle switch and is pivotal from "on" to "off" positions to activate or deactivate the circuit. The breaker also has an electromagnet or other means which trips or opens the circuit in overload, underload, over-voltage or under-voltage conditions. The electromagnet does not necessarily move the toggle switch from its on position when the circuit is tripped. The toggle switch is used, however, to reset or close the circuit after the breaker trips by turning the toggle to the "off" and then back to the "on" position.
The toggle switch allows the manager of a building or other structure to deactivate the associated circuit when it is not use, which is typically done at night to save energy. However, precautions must be taken to avoid turning off essential circuits, such as those required for night lighting, heating, security and/or refrigeration. Where many circuit breakers are on a panel board, however, it is easy to mistakenly deactivate the wrong circuit breakers at the end of a long business day. This, of course, can have disastrous consequences if perishables spoil or pipes freeze, for example.
Therefore, circuit breaker locks are employed to prevent the wrong breaker from being turned off. Heretofore, such locks typically have a collar which slidably fits onto the toggle switch and is secured thereto by screws which either screw into the bore provided through the conventional toggle switch or tighten the collar to grip the toggle switch, securing the lock to the toggle switch in either event. Such a lock also typically has a projection integrally formed with the collar, which abuts the circuit breaker housing if the switch is urged from its locked position, thereby preventing movement of the switch from that position.
Although such locks are quite effective, they are often difficult to remove, when removal is necesary to reset the associated circuit breaker. Circuit breakers are generally positioned close to each other in vertical columns on panel boards, switchboards or other control centers. When two or more adjacent circuit breakers have locks on them, the lock on one switch can prevent the lock on an adjacent, tripped breaker from being removed. This is due to the fact that the former switch creates an obstacle to the removal of the screw on the latter lock, since the screw often cannot be reached by a screwdriver without flipping the former switch. Of course, the former toggle switch cannot be flipped without removing the lock thereon. Thus, the lock on the former switch must be removed as well. If a series of adjacent switches have such locks, an entire row or column of locks may have to be removed to remove the lock on a tripped circuit breaker in order to reset the tripped circuit breaker in the manner described above, since each lock can be an obstacle to the removal of an adjacent lock. Needless to say, such an operation is time-consuming and frustrating.
A further disadvantage of prior art circuit breaker locks is that they typically cannot be made by the electrician on the job. Therefore, if the electrician exhausts his supply of such locks, he must stop work to go elsewhere and obtain more.